Welcome to Trolling Basics
Trolling is one of the best ways to connect with more fish more often. In the summer, fish found the shallows have now gone deeper or have likely spread out in a lake's open waters. Trolling is the only method that can present many lures at any depth, while covering such a broad section of water. There's more to trolling than simply dragging a lure behind a boat. There are a lot of trolling rigs, but only a few basic setups for trolling.
Trolling with a downrigger can run your lures deeper than any other method; trolling with this method will allow you to go as deep as a couple hundred feet, but 30'-60' is the most common in freshwater. Downriggers allow you to use light tackle, attached to an 8-12lb weight by a quick release clip and control your depth incredibly well. Downriggers can be setup with a single rod, double rod and are easy enough to use that one person can run multiple downriggers at once. If you've never used a downrigger before there is a lot going on - make sure you're paying attention first to the downrigger ball and second to your line; getting a downrigger ball stuck is one of the easiest ways to damage your boat/kayak.
When longlining, the depth you can fish is entirely dependent upon its weight, shape and design, as well as the speed the boat is traveling. Depending on what you're fishing, trolled lures or bait may only reach a maximum of 30 feet deep (without weight) or slightly deeper depending on the amount of weight used. Longlining is largely used when fishing diving plugs such as a shad rap or flicker minnow, these lures drive themselves to a set diving depth when enough line is let out. Longlining the easily the most simple form of trolling, but it does have it's challenges. Like other forms of trolling, fishing depth is always key to catching fish and longlining gives you less accuracy than downriggers - especially when changing lure types.